Upstream Bio Reports Third Quarter 2025 Financial Results and Highlights Continued Progress

– Positive top-line results from VIBRANT Phase 2 trial of verekitug in CRSwNP reported in September showed statistically significant and clinically meaningful effects on primary and key secondary endpoints when administered once every 12 weeks –

– On-track to report top-line results from VALIANT Phase 2 trial in severe asthma in the first quarter of 2026 –

– Enrollment ongoing in VENTURE Phase 2 trial in COPD; first patient dosed in July –

WALTHAM, Mass., Nov. 05, 2025 (GLOBE NEWSWIRE) -- Upstream Bio, Inc. (Nasdaq: UPB), a clinical-stage company developing treatments for inflammatory diseases, with an initial focus on severe respiratory disorders, today reported financial results for the third quarter ended September 30, 2025, and provided a summary of recent business highlights. The Company is developing verekitug, the only known antagonist currently in clinical development that targets and inhibits the thymic stromal lymphopoietin (TSLP) receptor, in multiple severe respiratory diseases including chronic rhinosinusitis with nasal polyps (CRSwNP), severe asthma, and chronic obstructive pulmonary disease (COPD). Verekitug’s unique pharmacology may lead to differentiated efficacy and an extended dosing interval as compared to the current standard of care.

“During this quarter we reached an important milestone in verekitug’s development and shared positive top-line results from VIBRANT, our Phase 2 trial in CRSwNP, which reinforced verekitug’s differentiated clinical profile, including its potential for efficacy meeting or exceeding that of available biologics, with administration only four times per year,” said Rand Sutherland, MD, Chief Executive Officer of Upstream Bio. “We also continued to bolster our understanding of verekitug through translational research, including with the presentation of new data identifying structural and mechanistic drivers of verekitug’s potent disruption of TSLP signaling by antagonism of the TSLP receptor at the European Respiratory Society Congress in September.”

“We remain on track to report top-line results from VALIANT, our Phase 2 trial in severe asthma, in the first quarter of 2026. Guided by these data, and following discussion with regulators, we will be well-positioned to advance our Phase 3 development plans for verekitug in both CRSwNP and severe asthma,” added Dr. Sutherland. “In addition, we continue to make investments in CMC and drug delivery with the goal of further strengthening the clinical profile and utility of verekitug for patients.”

Recent Business Highlights and Upcoming Milestones

• Positive top-line results from the VIBRANT Phase 2 trial in CRSwNP reported in September 2025:
  • Positive top-line results from the VIBRANT Phase 2 trial in CRSwNP showed statistically significant and clinically meaningful effects on multiple endpoints when administered once every 12 weeks.
    • In this 24-week study, VIBRANT met its primary endpoint, with verekitug dosed every 12 weeks leading to a statistically significant and clinically meaningful reduction from baseline in placebo-adjusted endoscopic nasal polyp score (NPS) of -1.8 (p